Ventilate MAC hub motor for cooler operation

Heat kills hub motors - especially my MAC geared hub motors. Why not ventilate a hub motor? Of course they are sealed to keep out the elements (read:water) but I think you could keep the inside of a vented motor dry enough.

In the mac motor, ventilation might best be done on the freewheel side. The windings are accessible under that side, the rotating permanent magnet and gear assembly covers the windings from the other side. Steps might be taken to "waterproof" the few exposed wires with high temp silicon, "weep holes" could even be put into the rim of the motor so that centripetal force would expel any liquid during rotation, a mesh could cover ventilation holes to block or slow most water trying to penetrate. Newly exposed and vaunerable parts might be sealed with paint, silicon or waterproof grease.

The vent holes themselves would need to be cut in a way to induce some airflow, or otherwise affixed with the suggestion of an airfoil to do so. I think a little bit of air movement might reduce temperatures significantly. This could be enough to keep wires from melting or sensors from failing.

What do you think? I'm just thinking out loud after two motors had sensor failure.

If dirt and rocks won't get into the gears from holes on the other side, It's worth a try. I just assumed you'd get dirt and dust in there, turning the gear lube into grinding compound.

I briefly tried air cooling on my Mac with no appreciable benefit. As mentioned above the biggest issue is dust getting into the gear grease. In the end I went with oil cooling which worked really well.

The most successful approach to cooling a geared hub is oil cooling. There is a thread on "oil cooling, not snake oil" and most deal with DD motors. But there a few who have tried with geared motors. I believe what I remember reading was the placement of the hole was important as you don't want it low enough where centrifugal forces let the oil seep out and onto your brakes. Also, the amount of oil is important as you don't want too much where the heating/expanding of the oil will make it leak as well. This can be remedied by inserting a pin size hole that allows the motor to breathe.

melodious said:

The most successful approach to cooling a geared hub is oil cooling. There is a thread on "oil cooling, not snake oil" and most deal with DD motors. But there a few who have tried with geared motors. I believe what I remember reading was the placement of the hole was important as you don't want it low enough where centrifugal forces let the oil seep out and onto your brakes. Also, the amount of oil is important as you don't want too much where the heating/expanding of the oil will make it leak as well. This can be remedied by inserting a pin size hole that allows the motor to breathe.

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Yup, the snake oil thread is mine. It's in my sig. :wink:

Yeas I wish there was a thread filled with facts about oilcooling a mac geared hub.
Cause that thread is a headache for a rookie like me.
And the searchfunction here on E-S is truly shite.
Rant over :-D

Now that I've tested a similar motor to destruction, I think the bottom line is not overloading a geared motor, or pushing more wattage than they can handle, in order to get better performance.

They do what they do great, helping a less than 300 pound total load climb hills to 10% or so, or steeper grades for short intervals with brisk pedaling. So if ya weigh 250, fuggetttaboutit.

The only way I can see pushing these geared motors any harder, would be using one for a mid drive, which could then be blower cooled.